1. Field of the Invention
The present invention generally relates to thermal cutting machines such as laser beam cutting machines and plasma arc cutting machines for cutting sheet-like workpieces such as sheet metals and more particularly to a dust collecting apparatus for collecting dust in the nature of molten metals or slags produced in such cutting machines.
2. Description of the Prior Art
As is well-known, thermal cutting machines such as laser beam cutting machines, plasma cutting machines and flame cutting machines are used to cut sheet-like workpieces such as sheet metals in many industries. During cutting operations of such cutting machines, dust in the nature of molten metals or slags including fine or minute particles are produced from the workpieces to be cut together with hot fumes by laser beam, plasma arc or acetylene flame at the working area.
Heretofore, it has been customary that the molten metal is collected by a bucket disposed just beneath the working area, while the fumes are disposed of by a filter of a dry exhaust system, so that foreign particles can be filtered from the fumes in order to provide a relatively clean discharge to the atmosphere. As the fumes, however, are passed through the filter, fine or minute particles such as chromium oxide, which is formed in the cutting of materials such as stainless steel, cannot be eliminated from the fumes and also the temperature of the fumes discharged into the atmosphere will remain high. Accordingly, it has been conventionally disadvantageous that the fine or minute particles of the molten metals and the heat of the fumes produced during cutting operations will pollute or contaminate the work environments of the thermal cutting machines. Furthermore, the bucket for collecting the molten metals or slags will be worn out early or will be shortened in its life by oxidization caused by high temperature of the molten metals, and otherwise it will be thermally deformed by the heat of the molten metals.